This invention relates to new and useful improvements in saw chain grinding machines.
Saw chains now in use have right and left cutter elements on alternate cutter links. Two common types of chain have hook-shaped cutter elements. One such common type, called the "chipper" or "round tooth" chain, has generally curved hook-shaped cutter teeth. The other common type, called the "chisel bit" chain, has generally L-shaped cutter elements with the side and top portions of each cutter element meeting at a sharp corner formed by precisely meeting angles. The oppositely directed cutter elements of such chains require grinding from opposite directions, and for the purpose of sharpening the cutter elements to provide a smooth and fast cut in the wood, the right and left cutter elements must all be ground uniformly.
In an attempt to achieve the best possible grinding of cutter elements, prior devices have been employed that seek uniform engagement of the opposite cutter elements with the grinding wheel. Also, to provide the desired angular engagement between the grinding wheel and the cutter elements, prior devices have used relative angles between the axis of the chain support on the machine base and the axis of the grinding wheel. A representative structure utilizing the relative angle arrangement between the axis of the chain support and the axis of the grinding wheel and for attempted uniform grinding is shown in U.S. Pat. No. 3,695,123. For the purpose of sharpening opposite cutter elements in this type of structure, the chain must be supported on separate holders disposed on opposite sides of the grinding wheel. Devices have also been employed which swing from one side of the grinding wheel to the other for engaging the oppositely directed cutter elements. Representative patents utilizing this latter type of structure comprise U.S. Pat. Nos. 4,287,793 and 4,539,871.
The structures as above defined which require that the saw chain be transferred from one side of the wheel to the other on different holders or which utilize a holder that is swung from one side of the grinder to the other all require a rather complex mechanism. Such complex mechanism makes it difficult if not impossible to precisely position mechanically opposite cutter elements for uniform grinding, particularly after wear of sharpening machine parts occurs. That is, such mechanisms require pivots or linkages or spaced mounting means which due to play or tolerances make it impossible to provide uniform grinding of all the opposite cutter elements.